docs: def get_alert_destination_count(self, channel=None):
          """Get the number of supported alert destinations
  
          :param channel: Channel for alerts to be examined, defaults to current
          """
          if channel is None:
              channel = self.get_network_channel()
          rqdata = (channel, 0x11, 0, 0)
          rsp = self.xraw_command(netfn=0xc, command=2, data=rqdata)
          return ord(rsp['data'][1])